Ultrastructural and molecular characterisation of the neuronal nucleus.

Within the mammalian nucleus, many major cellular functions are performed including transcription, pre-mRNA splicing and ribosome assembly, all of which are important for successful gene expression, and, to achieve this, the nucleus has evolved as a highly organised, dynamic structure (Dundr and Misteli, 2001). In this study a complete ultrastructural and molecular investigation of the neuronal nucleus has been undertaken, characterising three subdomains in detail: speckles, the nucleolus, and the Cajal body. It has recently been established that several human neurodegenerative diseases are associated with changes in the organisation of the neuronal nucleus, and this is believed to be the principle cause of cellular dysfunction and resulting clinical symptoms. Many of these diseases and their associated nuclear pathology have successfully been reproduced in transgenic mouse models. In this study I have determined the detailed ultrastructural and molecular organisation of the nucleus of neurons within the striatum of the mouse brain and compared this to nuclei of striatal neurons in a transgenic mouse model of Huntington's disease and in a mutant mouse lacking the gene for the protein p80 coilin. In the HD mouse there is a dramatic reorganisation of the nucleus accompanied by the formation of a novel nuclear subdomain, the neuronal intranuclear inclusion (Nil), which is associated with the movement of the Cajal body from the nucleolus to the Nil. This occurs with a change in the molecular composition of the speckles and a major reorganisation in the structure of the nucleolus. In contrast, the p80 mutant mouse is characterised by major alterations in the distribution and molecular composition of the Cajal body. However, this is not similarly associated with dramatic changes in either the speckles or the nucleolus. These studies clearly establish novel and important changes in the organisation of the neuronal nucleus associated with the formation of the Nil in Huntington's disease

Increase in Tau Pathology in P290S Mapt Knock-In Mice Crossed with AppNL-G-F Mice

Alzheimer's Disease (AD) is characterized by the pathological assembly of Aβ peptide, which deposits into extracellular plaques, and tau, which accumulates in intraneuronal inclusions. To investigate the link between Aβ and tau pathologies, experimental models featuring both pathologies are needed. We developed a mouse model featuring both tau and Aβ pathologies by knocking the P290S mutation into murine Mapt and crossing these MaptP290S KI mice with the AppNL-G-F KI line. MaptP290S KI mice developed a small number of tau inclusions, which increased with age. The amount of tau pathology was significantly larger in AppNL-G-FxMaptP290S KI mice from 18-months of age onwards. Tau pathology was higher in limbic areas, including hippocampus, amygdala and piriform/entorhinal cortex. We also observed AT100-and Gallyas-Braak-silver-positive dystrophic neurites containing assembled filamentous tau, as visualized by in situ EM. Using a cell-based tau seeding assay, we showed that sarkosyl-insoluble brain extracts from both 18-month-old MaptP290S KI and AppNL-G-FxMaptP290S KI mice were seed-competent, with brain extracts from double KI mice seeding significantly more than those from the MaptP290S KI mice. Finally, we showed that AppNL-G-FxMaptP290S KI mice had neurodegeneration in the piriform cortex from 18-months of age. We suggest that AppNL-G-F x MaptP290S KI mice provide a good model for studying the interactions of aggregation-prone tau, Aβ, neuritic plaques, neurodegeneration and aging

CD14+ macrophages that accumulate in the colon of African AIDS patients express pro-inflammatory cytokines and are responsive to lipopolysaccharide

BACKGROUND : Intestinal macrophages are key regulators of inflammatory responses to the gut microbiome and play a central role in maintaining tissue homeostasis and epithelial integrity. However, little is known about the role of these cells in HIV infection, a disease fuelled by intestinal inflammation, a loss of epithelial barrier function and increased microbial translocation (MT). METHODS : Phenotypic and functional characterization of intestinal macrophages was performed for 23 African AIDS patients with chronic diarrhea and/or weight loss and 11 HIV-negative Africans with and without inflammatory bowel disease (IBD). AIDS patients were treated with cotrimoxazole for the prevention of opportunistic infections (OIs). Macrophage phenotype was assessed by flow cytometry and immuno-histochemistry (IHC); production of proinflammatory mediators by IHC and Qiagen PCR Arrays; in vitro secretion of cytokines by the Bio-Plex Suspension Array System. Statistical analyses were performed using Spearman’s correlation and Wilcoxon matched-pair tests. Results between groups were analyzed using the Kruskal-Wallis with Dunn’s post-test and the Mann–Whitney U tests. RESULTS : None of the study participants had evidence of enteric co-infections as assessed by stool analysis and histology. Compared to healthy HIV-negative controls, the colon of AIDS patients was highly inflamed with increased infiltration of inflammatory cells and increased mRNA expression of proinflammatory cytokine (tumour necrosis factor (TNF)-α, interleukin (IL)-1β, IFN-γ, and IL-18), chemokines (chemokine (C-C motif) ligand (CCL)2 and chemokine (C-X-C) motif ligand (CXCL)10) and transcription factors (TNF receptor-associated factor (TRAF)6 and T-box (TXB)21). IHC revealed significant co-localization of TNF-α and IL-1β with CD68+ cells. As in IBD, HIV was associated with a marked increase in macrophages expressing innate response receptors including CD14, the co-receptor for lipopolysaccharide (LPS). The frequency of CD14+ macrophages correlated positively with plasma LPS, a marker of MT. Total unfractionated mucosal mononuclear cells (MMC) isolated from the colon of AIDS patients, but not MMC depleted of CD14+ cells, secreted increased levels of proinflammatory cytokines ex vivo in response to LPS CONCLUSIONS : Intestinal macrophages, in the absence of overt OIs, play an important role in driving persistentinflammation in HIV patients with late-stage disease and diarrhea. These results suggest intensified treatmentstrategies that target inflammatory processes in intestinal macrophages may be highly beneficial in restoringthe epithelial barrier and limiting MT in HIV-infected patients.This research and selected researchers (EC, TR, PM, SM and CS) were funded in part by a grant from the Delegation of the European Union to South Africa: “Drug Resistance Surveillance and Treatment Monitoring Network for the Public Sector HIV Antiretroviral Treatment Programme in the Free State – Sante 2007/147-790” and by a grant from the National Research Council of South Africa, Unlocking the Future 61509.http://www.biomedcentral.com/bmcinfectdisam201

Computerised Decision Support Systems for the management of freshwater radioecological emergencies: Assessment of the state-of-the-art with respect to the experiences and needs of end-users

Assessment of the environmental and radiological consequences of a nuclear accident requires the management of a great deal of data and information as well as the use of predictive models. Computerised Decision Support Systems (CDSS) are essential tools for this kind of complex assessment and for assisting experts with a rational decision process. The present work focuses on the assessment of the main features of selected state-of-the-art CDSS for off-site management of freshwater ecosystems contaminated by radionuclides. This study involved both developers and end-users of the assessed CDSS and was based on practical customisation exercises, installation and application of the decision systems. Potential end-users can benefit from the availability of several ready-to-use CDSS that allow one to run different kinds of models aimed at predicting the behaviour of radionuclides in aquatic ecosystems, evaluating doses to humans, assessing the effectiveness of different kinds of environmental management interventions and ranking these interventions, accounting for their social, economic and environmental impacts. As a result of the present assessment, the importance of CDSS " integration" became apparent: in many circumstances, different CDSS can be used as complementary tools for the decision-making process. The results of this assessment can also be useful for the future development and improvement of the CDSS. © 2010 Elsevier Ltd

Positron emission tomography of type 2 cannabinoid receptors for detecting inflammation in the central nervous system

Cannabinoid receptor CB (CBR) is upregulated on activated microglia and astrocytes in the brain under inflammatory conditions and plays important roles in many neurological diseases, such as Alzheimer's disease, amyotrophic lateral sclerosis, and ischemic stroke. The advent of positron emission tomography (PET) using CBR radiotracers has enabled the visualization of CBR distribution in vivo in animal models of central nervous system inflammation, however translation to humans has been less successful. Several novel CBR radiotracers have been developed and evaluated to quantify microglial activation. In this review, we summarize the recent preclinical and clinical imaging results of CBR PET tracers and discuss the prospects of CBR imaging using PET